Hypodermic syringe with distendable piston



Sept. 12, 1967 'r. s. cox 3,340,872

HYPODERMIC SYRINGE WITH DISTENDABLE PISTON Filed Nov. 24, 1964 United States Patent O 3,340,872 HYPODERMIC SYRINGE WITH DISTENDABLE PISTON Thomas S. Cox, 103 Hotel Ave., Knoxville, Tenn. 37918 Filed Nov. 24, 1964, Ser. No. 413,552 3 Claims. (Cl. 128218) ABSTRACT OF THE DISCLOSURE A hypodermic syringe having a tubular body and a piston plug slidably mounted therein. The piston plug has a distendable portion and a generally non-distendable support. A compound actuator having a first stem is adapted to engage the non-distendable support and a second stem, mounted for limited axial movement selectively and independently of the first stem, is adapted to engage and distend the distendable portion of the piston plug to aspirate the syringe when the second stem is actuated.

This invention relates to an improved hypodermic syringe for subcutaneous injection designed in a way to permit simple aspiration in a unique manner for a show of blood.

It is a principal object of the present invention to provide such a hypodermic syringe which is simple in construction, easily assembled and eificiently used.

A further object is to provide such a syringe which is normal in size for easy handling, may be sterilized in a conventional autoclave and operated with one hand.

A further object is to provide such a device wherein air may be dispelled from the barrel of the syringe or from a cartridge or ampule contained therein and will remain free of air bubbles without activating the aspirating means pro vided in the device.

A further object is to provide such a hypodermic syringe wherein the contents of the syringe may be injected in whole or in part with or without actuation of the aspirating mechanism at the will of the operator.

The syringe of the invention has particular utility where it is desired to inject an anesthetic in proximity to a nerve without fear that the needle is in a vein or artery where the anesthetics would cause severe physical reaction in the patient.

A further object of the present invention is to provide a hypodermic syringe which can be operated without the improved aspirating features on conventional non-aspirating cartridges and ampules.

These and other objects and advantages of the present invention will become more fully apparent tothose skilled in the art from the following detailed description considered in light of the appended drawings wherein:

FIG. 1 is a view of a hypodermic syringe constructed in accordance with the present invention which is adapted to receive replaceable cartridges or ampules;

FIG. 2 is an enlarged fragmentary partial sectional view of the device illustrated in FIG. 1;

FIG. 3 is a fragmentary partial sectional view of a portion of the structure illustrated in FIG. 2 with the aspirating plunger depressed; and

FIG. 4 is an enlarged fragmentary partial sectional view of a hypodermic syringe constructed in accordance with the teachings of the present invention employing a cartridge having a piston plug differing in configuration from the piston plugs illustrated in FIGS. 2 and 3 of the drawings.

In general, the hypodermic syringe of the invention comprises a tubular body member, a head portion communicating with the tubular body and adapted to receive a hollow injecting needle, a piston plug slidably mounted within the tubular body, said plug having a distendable portion and a generally non-distendable support therefor, a compound actuator for said piston plug, said actuator including a first stem, a finger-engaging head at one end of the first stem and a plug-engaging head at the other end of said first stern, a second stem mounted for limited axial movement selectively and independently of said first stem, a finger-engaging head at one end of said second stem and said other end of said second stem adapted to engage and distend the distendable portion of the piston plug when said finger-engaging portion of the second stem is depressed.

Referring to the drawings, 10 generally designates a hypodermic syringe embodying the principles of the present invention. The syringe 10 illustrated in the drawings is of the type adapted to receive a pre-filled cartridge or ampule 12 in a barrel or .body portion 14. The body portion 14 is provided with at least one elongated slot-like window 16 therein whereby the operator may visually check on the contents of the syringe and determine the position of the ampule piston plug 18 as to be more fully described hereinafter.

The lower end of the body portion 14 receives an adapter 20 which, in turn, replaceably receives a double pointed hollow hypodermic needle or cannula 22. The upper end of the body portion 14 has pivotally mounted thereon a head portion generally designated 24- which head portion has a pair of depending legs 26 which engage pivot pins 28, whereby the head portion 24 may be pivoted the lower end is provided with a piston plug engaging v head 38.

In the illustrated form of the invention, the piston plug engaging head 38 has a diameter only slightly less than the inner diameter of the ampule 12 thereby providing a substantial surface of engagement between the circular I face 40 of thehead 38 and the upper surface of the piston plug 18.

Slidably mounted within the hollow tubular stem 34 is a second stem 42. The upper end of stem 42 receives a finger-engaging head 44 which head 44 in the illustrated form of the invention is sized to be received within a recess 46 in the finger-engaging head 36 secured to the primary actuator stem' 34. The lower end of the inner stem 42 is of reduced diameter and is adapted to engage only a central limited portion of the piston plug 18.

As more clearly illustrated in FIGS. 2 and 4 of the drawings, the reduced diameter lower portion 48 provides a shoulder 50, which shoulder, in cooperation with the inner surface of a portion of the head 38 connected to the lower end of the primary actuator stem 34, engage opposite ends of a helical spring 52. The helical spring normally urges the inner stem 42 into an upwardly directed position as illustrated in FIGS. 1 and 2 of the drawings. The upward movement of the inner stem 42 is restricted by the shoulder 54 which engages a portion of the fingerengaging head 36 of the assembly. The lower limit of axial movement of the inner stem 42 is determined by the position of engagement between the under-surface 56 of head 44 and the lower end of the recess 46.

Referring particularly to FIGS. 2 and 3 of the drawings, the piston plug 18 is of generally cylindrical form and is constructed of resilient material whereby the outer cylindrical surface of the plug snugly engages the inner wall of the cartridge 12 whereby when the plug is depressed the contents of the cartridge are urged toward the needle end of the cartridge and out of the needle 22 when pointed end 58 thereof punctures the seal 60, illustrated in FIG. 1.

The piston plug 18 is provided with a central bore 6-2, which extends a substantial portion of the axial length of the plug to thereby provide a central generally resilient distendable portion 64. The resilience of the distendable portion 64 is enhanced by the annular bore 66, which bore is generally of a diameter equal to the recess 62 in the opposite end of the structure.

In operation of this form of the invention, the cartridge 12 is inserted within the body portion 14 and the needle point 58 is caused to puncture the end seal 60. Puncturing of the seal generally admits a small amount of air as the ampules are generally packed with a slight vacuum. Any air entering the cartridge 12 may be expelled by depressing the head 36, which causes the plunger 34 and stem 42 to move downwardly forcing the piston plug 18 to move toward the needle end of the device. This operation also fills the hollow needle 22 and reduces air embolism which might result if air were in the cartridge and the contents of the cartridge are injected into a patient. The surgeon may then insert the needle end into the tissue and such insertion may be accomplished by the desirable so-called pen grasp. It will be noted that releasing pressure on the plunger 36 does not effect aspiration and reinduce air into the cartridge 12. If the surgeon desires to determine if the needle is properly placed in a vein for intravenous injection or clear of a vein or artery where anesthetics are to be injected adjacent a nerve, the head 44 is depressed, which urges the inner stem 42 downwardly into engagement with the distendable resilient portion 64 of the piston plug 18. This movement of the stem 42 distends the lower portion 64 to a position as shown in FIG. 3, whereby upon release of the pressure on the head 44 the plunger stem 42 is urged upwardly by the spring 52 and the distended portion 64 of the piston plug 18 returns to its normal position, creating an aspirating effect within the cartridge 12, thereby drawing a small amount of blood into the cartridge if the needle is in a vein or artery. No blood would be drawn into the cartridge if the needle is free of a vein or artery. It will be appreciated that the force required to distend the resilient portion of the plug is less than the force required to move the plug within the cartridge.

In the form of the invention shown in FIGS. 2 and 3, the resilient distendable portion of the piston plug is positioned at the lower or inner end of the plug. The distendable portion may comprise a section of the upper or outer end of the plug. This form of the invention is illustrated in FIG. 4 wherein like parts are provided with reference characters identical with those. employed in the description of the form of the invention shown in FIGS. 1 through 3 and similar parts are provided with prime reference characters.

In FIG. 4 of the drawings, the piston plug 18 is provided with a bore 62', which extends from the lower surface 63 upwardly toward the upper surface 65. The bore 62' forms a resilient distendable element 64'. The element 64 is urged downwardly when the inner plunger stem 42' is moved toward the discharge end of the hypodermic syringe. The stem 42' is like stem 42 of the form of the invention illustrated in FIGS. 2 and 3, except that its length is reduced so that when the stem 42 is in its normal position, the extended end of the stem 42 is flush with the face 40 of the plug engaging head portion 38 which is movable with the primary plunger stem 34. In operation, this form of the invention functions in the same manner as the form shown in FIGS. 2 and 3.

While the invention has been described primarily in .4, reference to hypodermic syringes wherein the material to be injected is contained within a disposable cartridge or ampule, it will be appreciated by those skilled in the art that the principles of the invention would function equally well with a syringe wherein the body portion 14 is fitted with a piston plug such as piston plugs 18 or 18 and the material to be injected is drawn into the hypodermic syringe by upward movement of the piston plug. Where the syringe is to be filled by upward movement of the piston plug, means are provided for attaching or releasably attaching the piston plug to the lower end of the head portion 38 connected to the main stem 34 of the assembly as in conventional forms of hypodermic syringes.

From the foregoing description, it will be seen that the present invention fully accomplishes the aims and objects hereinabove set forth. It will be further recognized that certain changes may be made in the above-described constructions without departing from the scope of the present invention as defined in the following claims.

I claim:

1. A hypodermic syringe comprising a tubular body member, a head portion having an opening therein and disposed proximate one end of the tubular body, means disposed proximate the other end of said body to communicate a hollow injecting needle therewith, a resilient piston plug slidably mounted within the tubular body, said plug having a distendable central portion and a generally non-distendable support therefor, a compound actuator for said piston plug extending through the opening in said head portion, said compound actuator including a first slid-able stem, a finger-engaging head at one end of the stem and a plug-engaging head at the other end of said first stem, at second slidable stem mounted for limited axial movement independently of said first stem, a finger-engaging head at one end of said second stem, and said other end of the second stern adapted to engage and distend the distendable portion of the piston plug when said finger-engaging portion of the second stem is depressed.

2. The invention defined in claim 1 wherein said first and second stems are concentric.

3. A hypodermic syringe comprising a tubular body member, a head portion having an opening therein and disposed proximate one end of the tubular body, means disposed proximate the other end of said body to communicate a hollow injecting needle therewith, a piston plug slidably mounted within the tubular body, said plug having an axially distendable central portion and a generally non-distendable wall-engaging support therefor, a

compound actuator for said piston plug extending through the opening in said head portion, said compound actuator including a hollow stem, a finger-engaging head at one end of the hollow stem, and a plug engaging head at the other end of said hollow stem, a rod mounted for limited axial movement within said hollow stem and independently of said hollow stem, a finger-engaging head at one end of said rod, and said other end of the rod adapted to engage and distend the distendable central portion of the piston plug when said finger-engaging portion of the rod is depressed independently of said hollow stem.

References Cited UNITED STATES PATENTS 2,869,542 1/1959 Orsten et al 128-218 2,895,773 7/ 1959 McConnaughey.

FOREIGN PATENTS 373,594 4/1923 Germany. 1,000,756 8/ 1965 Great Britain.

RICHARD A. GAUDET, Primary Examiner.

D. L. BAKER, Assistant Examiner. 

1. A HYPODERMIC SYRINGE COMPRISING A TUBULAR BODY MEMBER, A HEAD PORTION HAVING AN OPENING THEREIN AND DISPOSED PROXIMATE ONE END OF THE TUBULAR BODY, MEANS DISPOSED PORXIMATE THE OTHER END OF SAID BODY TO COMMUNICATE A HOLLOW INJECTING NEEDLE THEREWITH, A RESILIENT PISTON PLUG SLIDABLY MOUNTED WITHIN THE TUBULAR BODY, SAID PLUG HAVING A DISTENDABLE CENTRAL PORTION AND A GENERALLY NON-DISTENDABLE SUPPORT THEREFOR, A COMPOUND ACTUATOR FOR SAID PISTON PLUG EXTENDING THROUGH THE OPENING IN SAID HEAD PORTION, SAID COMPOUND ACTUATOR INCLUDING A FIRST SLIDABLE STEM, A FINGER-ENGAGING HEAD AT ON END OF THE STEM AND A PLUG-ENGAGING HEAD AT THE OTHER END OF SAID FIRST STEM, A SECOND SLIDABLE STEM MOUNTED FOR LIMITED AXIAL MOVEMENT INDEPENDENTLY OF SAID FIRST STEM, A FINGER-ENGAGING HEAD AT ONE END OF SAID SECOND STEM, AND SAID OTHER END OF THE SECOND STEM ADAPTED TO ENGAGE AND DISTEND THE DISTENDABLE PORTION OF THE PISTON PLUG WHEN SAID FINGER-ENGAGING PORTION OF THE SECOND STEM IS DEPRESSED. 